This invention relates to the field of synthetic decorative coverings. More particularly, this invention relates to an apparatus and process for manufacturing synthetic decorative coverings and the products obtained thereby. It should be appreciated that "synthetic coverings" may be any coverings produced from organic components which may, if appropriate, include inorganic materials in their formulations (for example, asbestos or glass voile) or other organic materials of plant origin (i.e., jute).
The manufacture of products for synthetic decorative coverings, particularly for floors and walls, which are based on synthetic materials, usually polyvinylchloride (PVC), has been the subject of major developments in recent decades. Typically, these synthetic decorative coverings consist of a base material, such as, for example, jute fibers, asbestos, nonwoven glass fibers, synthetic foam or the like. Next, a sheet or layer of PVC is applied to the base. Finally, the face of the PVC receives a desired decoration or pattern and which thereafter, is usually protected by a transparent film covering.
A plurality of alternative methods for producing such decorative coverings have been utilized. However, all of these alternative processes relate to printing techniques which use a relatively viscous liquid product. Another technique, also derived from printing techniques, consists of localized application of plastisol studs by screen printing.
Because printing products are commonly used in the above discussed alternative processes, a pasty printing ink is also utilized in conjunction with these techniques. This ink is typically comprised, in part, of a liquid, i.e., water or solvent.
Generally, in order to produce the final decorative surface, known processes involve several successive applications, via printing techniques, of various components of the decoration. Each printing application requires a drying step after which, a transparent protective covering is employed.
It will be appreciated to those skilled in the art, that the above processes provide only mediocre results, particularly when attempting to imitate ceramic glazes such as floor tiling or wall tiling. Various improvements in the above processes, involving the use of foaming agents in conjunction with simultaneous and localized application of chemicals which retard or accelerate foaming, have been proposed in an effort to produce a localized expansion (for example, see FR-A No. 1,411,338). However, even in this French patent, it has been found that while the geometrical configuration and appearance of the tiling can be accurately reproduced, the surface conditions peculiar to glazed products is reproduced only sporadically and the appearance of a depth (also peculiar to these ceramic products) is not achieved.
Patents DE-A No. 2,260,788 and FR-A No. 2,263,893 disclose "handicraft" processes for producing patterns by the deposition of fusible substances on a base made of metal, glass, ceramic or of any other material which is stable at the temperature for carrying out the subsequent thermal treatment. These processes are intended for use in the non-continuous production of colored patterns in the form of, for example, tourist souvenirs or the like.
Patent FR-A No. 74/37,741 describes a process for printing textile surfaces, particularly deep pile materials, wherein coloring products having a powdered form are applied to the surface which is to be printed in accordance with a corresponding decorative design. A portion of the colored product is then fixed. Any particles which were not fixed are subsequently removed. This French patent relates solely to textile surfaces and does not in any way teach or suggest a process for providing a covering which imitates the glazing effects generally obtained with ceramic materials. To the contrary, the printing process described in FR-A No. 74/37,741 relates to depositing a dye on a piled textile by a technique involving disposing powdered colorants in the interstitial spaces of the textile fibers. It will be appreciated that this process essentially depends on the base material and the preparation thereof. The purpose of the process is to provide a final decorative effect which is restricted to introducing coloring into textile fibers without providing any three dimensional effects.
Prior art patent CH-A No. 595,145 discloses the deposition of powders through a screen printing frame which is in contact with the base material by means of a magnetic doctor blade. The technique of this patent does not permit a variable volume of powders to be disposed on the base.
Finally, a process suggested by Patents FR-A No. 2,291,868 and FR-A No. 2,210,148, involves the fixation of particles, fibrils or powders, under the effects of an electrostatic field onto a base coated with an adhesive material.
It should be understood to those skilled in the art that the above discussed techniques and processes are not applicable in any satisfactory way to the manufacture of flexible multilayer decorative coverings for floors and walls having requirements which include, for example, high resistance to delamination and other stresses.